/**
 * @Author:  蓝建平
 * @Description:
 * @Date:  2019/12/4
 */
void main()
{
  var a=20;
  const b=20;
  print(a==b);
  String strA="abc";
  String strB="abc";
  print(strA==strB);

  var isTrue=true;
  var isFalse=false;
  print(!isTrue);
  print(isFalse && isTrue);
  print(isTrue || isFalse);
  int a1=10;
  int b2=10;
  b2 ??=29;
  print(b2);

  String aa1="Dart";
  String aa2="Java";
  String aa3= aa1??"PHP";
  print(aa3);
}